Let this column – a republican, ever since the usurpation of the enlightened elective monarchy of the Anglo-Saxons by those thugs, the Normans – at least join in the jamboree by celebrating the timely reprint of this little gem. You may well have read it already. You should have. It was first published in 2006 in the LRB, and released as a hardback in 2007. If there is only going to be one good thing to come out of the jubilee, let it be this.

The plot, for those unfamiliar with it: the Queen, herding unruly corgis, discovers a mobile library parked by the Buck House kitchens. Noblesse oblige and all that, so she borrows a book – Ivy Compton-Burnett – and then, despite its being a slog, she borrows another (Nancy Mitford – more to her taste) and another ... and with the help of Norman, the autodidact gay kitchen porter, becomes an avid reader, eventually reading Proust at Balmoral instead of shooting stags. Her courtiers hate the habit; they perceive – hilariously – that reading is "elitist", and suspect incipient dementia.

Bennett's jokes are so beautifully modulated that I would rather not spoil them. But he is subversively sound, I think, on the nature of the monarchy. There are two good reasons for its abolition: it infantilises us, and, in turn, it deranges the royals. Bennett illuminatingly imagines the Queen being at first daunted by Jane Austen: so far distant in terms of rank, she is unable to appreciate the – to her – relatively small social divisions between Austen's characters. This is the most polite way imaginable of accusing the Queen of being out of touch; but then, as Bennett observes, commoners too lose their minds when summoned to the presence. Look at poor Andrew Marr's The Diamond Queen, for instance.

The mistake, of course, is to see Elizabeth "Windsor" as a person. "She ain't no human being," as John Lydon correctly observed in 1977; she's a constitutional construct. If the blandness of her public utterances, or phatic questions to those who have come to be ennobled by her ("have you come far?" and so on; Bennett has commoners freaked out when she starts asking them what they've read lately instead) can exasperate, one can expect nothing more from a figurehead, whose expression must remain the same whatever the weather. (One perversely looks forward to the ascension of Prince Charles, who seems to entertain no such concept of discretion, and who might wear out public acceptance of the hereditary principle even before his reign ends in the traditional manner.)

Hence our desire to draw expressions on the blankness, and the way she is said to pop up in our dreams (do republicans dream less of her than monarchists?). Like Jesus, she is an idealised projection of our own best selves, which is why Bennett has mapped his own literary sensibilities, more or less, on to hers.

As with the popular children's work, The Queen's Knickers, The Uncommon Reader is a piece of audacious lèse majesté which, in an earlier age, would have put its author's head on a spike. (As I write these words, I am still reeling from the news that an allegedly genuine pair of the Queen's knickers has been sold for £11,000 on eBay.) It is a testament to Bennett's extraordinary skill – his genius, even – that we assent to the proposition, which would in real life make a cat laugh, that the Queen could be capable of becoming a reader of fine discernment. And not only that: but also that we can imagine her making the wonderful speech at the end of the book ("one has given one's white-gloved hand to hands that were steeped in blood ..."). It is a fantasy on the same level of wish-fulfilment but with, I suspect, even less basis in reality than Hugh Grant's speech standing up to the Americans in Love, Actually.

The difference between that wretched film and this book is that Bennett knows what he is doing. (After a disastrous party she stuffs with writers: "Authors, she soon decided, were probably best met with in the pages of their novels ...") And it isn't really about the Queen at all. It's about literature, the ultimate democracy.